Hydraulic motor



April,28, 1942. 'J. A. MULLER 2,281,372

HYDRAULIC MOTOR I Filed Sept. 9, 1938 4 Sheets-Sheet l Jmm JBHAN A. MULLER,

A ril 28,1942." .LA. MULLER 2,281,372 nymuwuc MOTQR Filed Sept. 9, 1938, 4 Sheets-Sheet 4 pi m Patented Apr. 28, 1942 HYDRAULIC MOTOR Johan A. Muller, Mount Gilead, Ohio, assignor to The Hydraulic Development Corp. Inc., Wilmington, DeL, a corporation of Delaware Application September 9, 1938, Serial No. 229,215

3 Claims. (01. 0-52) This invention relates to hydraulic motors, and in particular, to reciprocating motors.

One object of this invention is to provide a hydraulic motor having a reciprocating plunger which moves at the same rate and distance as a control member, but delivering a much greater force than is applied to the control member.

Another object is to provide a hydraulic motor having a reciprocating plunger with a piston valve member cooperating with ports in the head of the plunger so as to provide a point-for-point travel of the plunger with the piston valve memher, but with the output or a relatively great force for a given force applied to the piston valve member.

Another object is to provide a hydraulic motor having. a reciprocating plunger with a head having a chamber therein, with ports cooperating with the head of a piston valve member in such a manner as to uncover one of these ports to permit pressure fluid to flow through the plunger head to the opposite side thereof when the piston valve member is moved in one direction, but to uncover another port permitting the discharge of pressure fluid from one side of the plunger head when the piston valve member is moved in the opposite direction, thereby providing a follow-up motion of the plunger in correspondence with the motion of the piston valve member.

Another object is to provide a hydraulicmotor having a plunger with a head having a passageway therethrough, and a piston valve member cooperating with the ports in the plunger head, the passageway thereof having a check valve therein operated in such a manner as to by-pass and unload the discharge from the source of pressure fluid when the plunger reaches a predetermined limit of its stroke in one direction. I

Another object is to provide a hydraulic motor of the type set forth in the preceding paragraph, wherein the piston valve member is arranged to mechanically engage the plunger so as to advance the latter mechanically to provide a rapid I utilizing the motor oif the foregoing objects, for

actuating the ram thereof in follow-up relationship with the manually shifted piston valve member.

Another object is to provide a hydraulic motor having a plunger with a head providing a diilerential piston area when pressure is admitted simultaneously to both sides of the head, together with means controlled by a control member for selectively admitting or cutting ofi the supply of pressure fluid to one side of the plunger head so as to selectively provide or eliminate the differential efiect and cause the plunger to move in opposite directions.

In the drawings:

Figure 1 is a central longitudinal section through a hydraulic motor according to the present invention.

Figure 2 is a cross section along the line 2-2 in Figure l.

Figure 3 is a diagrammatic view of a simplified hydraulic circuit for operating and utilizing the traverse of the plunger to the working position instead of having to wait until the pressure from the pressure source forces the plunger to th working position.

Another object is to provide a hydraulic motor unit employing the hydraulic motor set forth in the preceding objects, the unit having" a selfcontained motor and pump together with a relief valve and a check valve for enabling the motor unit to be operated as a single entity without the v need for external piping.

Another object is to provide a hydraulic press hydraulic motor of Figures 1 and 2. g

Figure 4 is an enlarged view of a portion of Figure 1, showing the relationship of the parts when the motor plunger is set for operation in an upward directi0n.

Figure 5 is a view similar to Figure 4, but with the parts set for operation in a downward direction.

Figure 6 is a front elevation of a modification consistingof a hydraulic press utilizing the hydraulic motor of the present invention, and providing a self-contained pump unit associated therewith.

Figure 7 is a central longitudinal section through the lower part of the press shown in Figure 6, illustrating the construction of the pumping unit.

Figure 8 is a diagrammatic layout of the circult of the pump and valves shown in Figure 7.

Figure 9 is an enlarged view of a portion of Figure 7, with the plunger at-its lowermost position, showing the means for lay-passing the discharge of the pump in that position.

,Figure 1c is a view similar to Figure 9, but showing the motor plunger being rapidly traversed mechanically by the direct mechanical application of the piston valve thereto instead of relying upon hydraulic pressure.

General construction In general, the hydraulic motor of this invention consists of a cylinder with a double-acting plunger therein. The plunger has a head with one direction or the other.

passages from opposite ,sides communicating with ports in a chamber within the head, these ports cooperating with the head of a piston valve member in such a manner as to selectively open and close one orthe other of the ports. When one port is uncovered by the piston valve head, pressure fluid is enabled to engage both sides of the plunger head andurge the latter in one direction as a result of the diflerential piston area provided by the rod portion of the plunger. when this port is covered and the other port uncovered, however, fluid is permitted to act against but one side of the plunger head. thereby urging I the plunger in the opposite direction. The device gives a follow-up motion by reason of the fact that when the piston valve head is moved a given distance in one direction, the uncovering of the ports within the plunger head causes the plunger to be moved in the same direction as the piston valve head, thereby again covering up the ports when a like distance has been traveled by theplunger head as was traveled by the piston valve head. The motor of this invention, however, gives a greatly increased mechanical advantage because the force produced by the motion .of the plunger is vastly greater than the force necessary to move the piston valve head in In other words, a point-for-point correspondence is eifected be,- tween the motion of the piston valve member and the resulting motion of the plunger.

This invention is capable of use as a servomotor or as an auxiliary motor for controlling the servomotors of large hydraulic pumps. It may be used, however, in any position where it is desired to obtain a greatly increased force with a corresponding rate and distance of motion, such as in controlling the positions of members in heavy machinery, such as .steelmill machinery. Another application is for regulating the position of the blade of a road grader so as to regulate the depth of cut. Still another application is that of a smaller press, such as for forcing bushings for riveting or for assembling. The device may also be used as a hydraulic jack or hoist.

A modification of the invention, as shown in Figures 6 to 10, utilizes the motor of Figures 1 to 5 with a built-in pump unit, together with means for by-passing the discharge of this pump unit when the motor piston reaches the end of its stroke in one direction. The piston valve member in this modification is made to directly engage the motor plunger when the latter is in its retracted position, so that the motor plunger may be rapidly traversed to the work by the force exerted by the operator himself, rather than requiring a wait for the action of the hydraulic pressure. Under such circumstances, a check valve is provided for admitting fluid to the space behind the head of the motor plunger.

Hydraulic motor Referring to the drawings in detail, 'Figure 1 shows a preferred embodiment of the hydraulic motor of this invention as consisting of a casing ill with bores II and I 2 therein, separated by an annular partition l3 having a bore H with a bushing i5 therein. The bushing l5, .which may be a bronze bushing, fits closely around the motor plunger i6 so as to prevent excessive leakage. The motor plunger IB is provided with a .head i! having L-shaped passages l3 and is communicating with ports 20 and 2i in a sleeve 22 mounted within a longitudinal bore 23 withsageway 26 extending through the plunger ii to the cross passages 21 opening out into the bore l2. Beyond the cross passages 21 the motor plunger I 6 passes through an annular end wall 23, having beyond it a packing 29, compressed by a gland 30, for preventing leakage from the device. Threaded ports- 3| and 32 open, respectively, into the bores I I and I2. The port 3i serves as an inlet port for pressure fluid, and the port 32 as an outlet port for the discharge of fluid. The inner surface 33 of the sleeve 22 forms a bore for receiving a piston valve head 34 upon a piston valve rod 35, having a reduced diameter portion 36 connecting it with the head 34. Se-

cured to the end of the sleeve 22, as by the screws the casing II by the screws ll, and containing a packing 4i compressed by a gland 4 2 for preventing leakage around the valve rod 35. Also mounted upon the cylinder head 33 is a bracket 43, having a pivot pin 'pivotally supporting one end of a hand lever ll having a slot 43 engaging a pin 41 in the end of the valve rod 35. By mov: ing the hand lever 45 the valve rod 35 may be shifted to and fro, and with it .the valve head 34. It will be understood, however,- that the provision of the valve operating lever 45 is merely for convenience, and that any other means of moving the valve rod 35 may be adopted,'such as a knob upon the valve rod 3!.

Figure 3 shows one application of the motor of Figure 1, wherein the plunger It carries a clevis 48 carrying a pivot 43 passing through one arm 53 of a bellcrank, generally designated II, the other arm 52 of which is provided'with a similar pivot pin 53 passing through a clevis 54, attached to a rod or'link 55. The bellcrank II is itself mounted upon a pivot shaft 56. The rod 55 may consist of the servomotor valve rod of a large hydraulic pump of the type having a movable flow-control element controlled by a servomotor, such as that shown in the Ernst Patent No. 2,038,272, issued April 21, 1936. The casing 10 is provided with bosses 51" and 58 surrounding the ports 3| and 32. Connected to the port 3! is a conduit 59, constituting the pressure conduit from a pump 60, the latter having a suction conduit 8| extending downwardly into a fluid tank 62, Connected to the port 32 is a discharge conduit 63, likewise leading downwardly into the tank 62.

In the operation of the hydraulic motor of Figures 1 to 5, the pump 60 delivers pressure fluid through the conduit 59 and port 3!, into the bore I I, whence it passes downwardly through the L-shaped passageway i8, into the port 20. If, now, the valve rod 35 is moved upwardly (Figure 4), the valve piston head 34 thereof uncovers the port 20 so that pressure fluid can flow onward through the bore 33 of the sleeve 22, into the space beneath the plunger head ll. The latter is provided with upper and lower head areas 64 and 65, respectively, the difference between these areas providing a differential piston area which is eflective when both of the head areas 64 and 65 are supplied simultaneously with pressure fluid. This occurs when the upward motion of the valve rod 35 and valve head 34 uncovers the sleeve port 20 so that pressure fluid acts simultaneously upon the small annular area 64 and the large annular area 65. The effective piston head area thus brought into play is equal to the difference between the areas of the portions 64 and 85, with the balance in favor of the lower head area 65. As a consequence, the plunger head 11 and plunger l are moved upwardly. When this occurs, however, the port is moved upwardly until it passes the lower edge of the valve head 36, again covering upthe port 20. The'port 2!, meanwhile, has been covered up in the initial raising of the valve rod 35, thereby cutting oil communication between the head passageway it and the longitudinal bore 26 in the plunger 06. If the valve rod is moved upwardly a given distance, therefore, the plunger head 91 and plunger it will move upwardly a corresponding distance. As the piston valve head 3-3 is a small piston, however, it is easily moved with little eflort on the part of the operator, whereas the plunger head l1, because of its large area, exerts a much greater force on the plunger it than it is necessary to apply to the valve rod 35'to move the valve piston head 34.

If it is desired to move the plunger IS in the opposite direction, the operator shifts the hand lever 45 to move the valve rod 35 downwardly (Figure 5) carrying with it the valve piston head 3 and uncovering the port II in the sleeve 22. This opens up the L-shaped head passageway IQ for communication through the port 2| with the longitudinal plunger passageway 26, and at the same time closes oil the port 20 and the L-shaped head passageway 18 against the discharge of pressure fluid therethrough. As a result the pressure fluid from the pump 69 is applied solely within the upper end of the bore ll against the annular plunger head area 84,- and all pressure is released against .the lower plunger head area 65 The plunger 96, therefore, moves down-, 'wardly, the fluid displaced from beneath it moving upwardly through the passageway I9, the port 2 l, the counterbore 24, the plunger passageway 26, the cross passageways 21, the cylinder bore It, the outlet port 32 and the conduit 83, into the tank 52. The plunger head I1 and plunger l6 move downwardly until the port 2| port 20 has been covered up by the piston valve head 34.

In this manner. it will be seen that when the operator shifts the valve rod 85 and valve head 35 a given distance in one direction, the plunger It will move exactly the same distance in the same direction and halt. During its motion, however, the plunger ltwill make available a vastly greater working force than the force applied in shifting the valve rod 35, due to the greater head area of the plunger head l1. Thus, in an upward direction of motion of the valve rod 85, both of the plunger head areas 68 and 58 are brought into operation simultaneously, with the resulting application of a plunger head area equivalent to the difference between these two' areas. In a downward motion of the valve rod 35 and valve head 38, however, the lower plunger head area is prevented from receiving pressure fluid and at the same time is-connected to the discharge circuit so that it is under substantially zero pressure. When this occurs the upper plunger head area 64 alone operates to move the plunger I6 downwardly. If this area 64 is made very small by making the plunger l6 of nearly the same diameter as the plunger head I1, a very rapid downward motion of the plunger It can be brought about. This is valuable when it is desired to advance the plunger l6 upwardly at a slow rate with the production of a great force, yet to retract the plunger lfiin a downward direction at a high rate of speed.

Hydraulic machine with self-contained pumping unit The hydraulic machine shown in Figures 6 to 10, inclusive, utilizes the hydraulic. motor of Figplunger head of the motor reaches the extreme limit of its stroke in one direction. The parts of the motor itself, in general, remain unchanged to a substantial extent, and are designated with like numerals to those employed in Figures 1 to 5. The plunger head l1, in Figure 7, however, is provided with an additional passageway 10, containing a check valve plunger 11 with flutes 12 and guides 13. The cylinder head 39 is provided with an annular internal shoulder 14 positioned to engage and lift the check valve plunger 1| when the main plunger head 11 reaches the lower limit of its position,therebyunloading the discharge of the pump in the manner hereinafter explained. The casing It at its upper end, in Figure 7, is provided with an exprevents the covering up or restriction of the cross passages 21, which would otherwise occur when they passed into the extension 15.

In the plunger l6 of Figure '1, the counterbore 26 at the upper end of the bore 23 has been omitted. In the lower positions of the plunger it, this construction permits the upper end of the valve piston head 36 to engage the annular projecting portion 19 of the end wall 25. The lower end of the valve rod 35 carries spaced collars 80, engaged by the yoke 8! upon the end of the foot pedal 82. The latter is pivotally mounted upon the shaft 83, supported by the bracket 86 extending upwardly from the base 85, the latter having an aperture 86 and recess 81 for receiving and supporting the cylinder head 39. A spring 88, connected as at 89 to the foot pedal 82 and at W to a fixed abutment, such as the base 85, constantly urges the yoke 8| and valve rod 35 downwardly towardits lowermost position. The upper end of the casing i0 (Figure 6) is provided with a cross member 9|, either integral therewith or attached thereto and serving for the connection of strain rods 92, the upper ends of which are secured to the press head 93. The strain rods 92 terminate in nuts 96 upon the threaded ends thereof. In Figure '7 the strain rods 92 and head 93 have been omitted. This structure is omitted when the device is used as a hydraulic Jack, or for similar purposes. Instead of the strain rods 92 and head 93, a frame of any other type may be provided, such as for example, an open gap frame, as is understood by those skilled in the hydraulic art.

For supplying pressure fluid for the operation of this device the casing I0, in Figure 7, is provided with a hollow casing extension 95, containing an inner chamber 96 serving as a fluid tank or reservoir. Mounted in this chamber 96 is a check valve, generally designated 91, having a port 99 engaged by a check valve ball 99, adapted to move up and down in the recess I within the screw plug IOI. When the ball 99 is raised the port 98 communicates with a chamber I02, connected by the passageway I03 to the lower end of the cylinder bore II. The .middle portion of the casing extension 95 is occupied by a pressure relief valve, generally designated I04, having a reciprocable valve member I urged upwardly by a spring I06 within the cap I01, threaded into the valve casing I09. The cap IN is protected by a threaded cover I09. The mid-portion of the relief valve member I05 opens into a chamber IIO, whereas the upper portion III opens into a chamber II2, directly connected to the passageway II3 opening into the top of the cylinder bore I2, in a manner analogous to the port 3| in Figure 1. The relief valve I04 in its details forms no part of the present invention, and is disclosed in the Ernst Patent No. 2,086,295, issued July 5, 1937.

Above the pressure relief valve I04, at the upper end of the casin extension 95, is a pump, generally designated 4, and including a pump chamber I I5 containing intermeshing pump gears H6 and III. One side of the chamber II5 opens into the suction port II9, connected by the suction conduit I I9 to the bottom of the reservoir or chamber 96. The other side of the pump chamber II5 opens into the pressure port I20, from which the conduit I2I runs to the port I22, opening into the upper relief valve chamber H2. The pump gears H6 and III are mounted upon shafts I23 and I24. The shaft I23 is connected to an electric motor I25 and driven thereby. ,The details of the gear pump II4 form no part of the present invention, and are disclosed in the Ernst Patent No. 2,103,524, issued December 28, 1937. Beyond thesuction port II9 the passageway I26 continues, opening into the upper cylinder bore I2 in a member analogous to the port 32 of Figure 1, and connecting the upper bore I2 with the reservoir chamber 96 by means of the downwardly extending suction conduit H9. The upper end III of the relief valve plunger I05 opens into the passageway I21, connecting it with the conduit II9. In order to move the relief valve plunger I05, the latter is provided with a passageway I29 extending from the chamber II2 to the chamber I I0. A passageway I29 also extends through the" relief valve plunger I05, from end to end, and

' provides for drainage.

ber '96, through the conduit H9 and port II9, into the pump chamber I I5, discharging it under pressure through the pressure port I20, the passageway I2I and the port I22, into the relief valve chamber II 2, thence through the passageway III, into the lower cylinder bore II, whence the fluid proceeds through the L-shaped passageway I9 and the now open check valve passageway 10, into the space beneath the plunger head II.

The spring 09, meanwhile, holds the valve rod 35 in its extreme lowermost position, thereby uncovering the port 2| from closure by the valve piston head 34 and opening communication between the L-shaped passageway I9 and the bore 33, by way of the now uncovered port 2I. Fluid discharged by the pump into the space beneath the plunger head II, in the manner previously described, is then exhausted through the passageway I9, the port 2I,' the plunger passageway 26, the cross passages 21, the upper cylinder bore I2, the passageway I26 and the port H9, into the pump chamber H5. The pump is therefore free to continue to run and circulate oil at no pressure so long as the valv rod 35 and valve piston head 34 are in their lowermost positions. In this condition, therefore, when the plunger head II lies in its lowermost position, the discharge of the pump is completely unloaded at zero pressure.

To cause the plunger I6 to move upwardly on a rapid traverse stroke, the operator merely steps'on the foot pedal 82. When he does this the upper end of the valve piston head 34 engages the shoulder I9 within the plunger I6, and forces not only the valve rod 35 but also the plunger I6 upwardly. In this manner the operator can move the plunger I6 upwardly to the work at a more rapid rate than would be possible with the use of the pressure fluid alone. The suction created beneath the plunger head I! is filled with fluid reaching it from the reservoir '96, past the ball 99 of the check valve 91 and through the passageway I03. The check valve plunger II, of course, closes immediately after its removal from engagement with the internal shoulder I4 as soon as the plunger I'I rises. Thus the operator is not obliged to wait for the pressure fluid to raise the plunger I6, but can force the entire plunger assembly upward until the plunger encounters the workpiece.

Meanwhile, (Figure 10), as soon as the operator has raised the valve piston head 34 past the port 20, pressure fluid is free to discharge through the L-shaped passageway I8 and port 20,1nto the space beneath the piston head 65, likewise assisting in filling the space therebeneath; When theplunger I6 halts upon engagement with the workpiece and builds up resistance so that the operator can raise it no further with foot pressure, the pressure fluid acting upon the plunger head area 65 builds up and urges the plunger upwardly. At this time the port 2I is, of course, closet: bythe valve piston head 34 so that fluid cannot escape from the lower portion of the cylinder bore II. The operation of the motor is henceforth similar to that described in connection with Figure 1. By making the plunger I6 almost as large as the plunger head I'I, so that the annular head area 64 is very small, the plunger I6 may be retracted at a rapid rate even though the pump II4 has but a small delivery.

To retract the plunger I6, the operator removes his foot from the foot pedal 92, whereupon the spring 9| pulls the valve rod 35 and valve head 34 downwardly, closing the port 20 and uncovering the port 2|. In the manner previously described-in connection with Figure 1, this allows fluid to be exhausted from the space beneath the plunger head I! while pressure is built up above the latter, causing it to beretracted. The plunger head ilandplunger it continue to move downwardly until the plunger head l'lcomes to rest against the internal shoulder 15, which then raises the check valve plunger H (Figure 9) and again causes the pump! to by-pass its dischargeat zero pressure. in the manner previously set forth. Forthesake of simplicity of showing, the check valve ball 99 and check valve plunger ii are shown as urged downwardly by gravity. By spring loading the ball 99 and plunger 1 i the motor may be enabled to operate horizontally, vertically or in any other position. Y Y

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims. I

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a hydraulic motor unit, casing means having a cylinderbore. a pier reciprocable in said-bore and having a hmd with a M geway therethrough, a pump mounted on said I casing means and connected to deliver pressure fluid to said cylinder bore on one side of said head, a valve" member positioned to selectively openand close said passageway to admit and exclude pressure fluid respectively irom the other ,side or id head, said valve member being adapted to physically contact said plunger throughout a, portion of its stroke for moving said plunger aportion of its stroke in response to a manual movement of deliver pressure fluid to said cylinder bore on one side or said head, a passageway leading from the other side 01' said head to said exhaust; bore, a

valve member positioned to selectively open one passageway while closing the other passageway. said valve member being adapted to physically contact said plunger throughout aportion of its stroke for moving said plunger 9, portion of its stroke in response to a manual movement otsaid valve member whereby to rapidly traverse said plunger to its working position by means of said valve member, and valve means for admitting fluid behind said plunger tofill the space evacuated by the motion of said plunger by its mechan ical engagement with said valve member. a

3. A hydraulic motor comprising a cylindrical casing containing a plunger terminating in a piston head of greater diameter than said plunger 1 piston head along the. casing, means for admitting said valve member whereby-to rapidiyrtraver se said plunger to its working positionbymeans of said valve member, and valve means" for ting fluid I behind said plunger space evacuated by the motion of said plung as its mechanical'engagement with said-'valve'iniember.

2. In a hydraulic motor unit, casing i'neans having a cylinder bore and an exhaustgbprea plunger passing through said bores and having a head with unequal head areas on opite sides whichis reciprocable in said cylinder bore, mid head having a passageway therethroush, a pump fluid into the space between the piston head and the casing left during the manual movement of theqpiston' head, and means for power driving the piston head at the conclusion of the manual movement, said last-mentioned means including adevice i'or admitting pressure fluid simultane- 1, o to that side of the piston head to which the lea to the opposite side 01 the piston head plunger is secured and also to the passageway through an uncovered port in said sleeve, whereby fluid on opposite sides or the piston head is power driven in the same direction as the manual movement due to the total difierence oi pressure exerted by the pressure the piston head. i JO? A, i 'l 3,1'

mounted on said casing means and connected to 

